1. Field of the Invention
This invention relates to a pump utilizing a helical seal arranged between the inner peripheral surface of a barrel member and the outer peripheral wall of a cylindrical core member eccentrically inserted into the barrel member so that the capacity of an airtight helical fluid path defined by the helical seal, the barrel member and the cylindrical core member is made to continuously change as the helical seal is rotated (including rotation and revolution due to the relative rotary motion of the cylindrical core member and the barrel member) and the liquid introduced into the helical fluid path is forcibly discharged from an axial end of the barrel member.
2. Related Art Statement
Known devices comprising a barrel member and a cylindrical core member concentrically housed in a barrel member to define a helical fluid path at the contacting surface portion of the members for transforming fluid energy include (1) those designed to control the pressure or the flow rate of fluid flowing through the helical fluid path, (2) those designed to operate as a pump that forces the fluid in the helical fluid path to move forward by rotating either of the members on which the helical fluid path is arranged and (3) those designed to operate as a hydraulic turbine that causes pressurized fluid to flow through the helical fluid path in order to drive either of the members on which the helical fluid path is arranged to rotate. More specifically, known devices of the types under consideration includes a fluid control device disclosed in Japanese Patent Application Laid-Open No. 63-67496 and a rotary transmission device disclosed in Japanese Patent Application Laid-Open No. 63-163067.
The inventor of the present invention has proposed a fluid energy transforming device comprising a barrel member, a cylindrical core member concentrically housed in the barrel member and a helical seal fitted into a helical groove provided at the contacting surface portion of the members so that the device may operate as a pump. As the barrel member or the cylindrical core member is driven to rotate, the helical seal revolves to make the fluid flowing through the helical fluid path along the helical seal subjected to an axial pushing force to raise the pressure of the fluid.
Known pumps utilizing a helical groove include a stator for an eccentric screw pump disclosed in Japanese Patent Application Laid-Open No. 50-22310 and a displacement axial-flow rotary piston disclosed in Japanese Patent Application Laid-Open No. 54-14008, which are designed to apply pressure to and discharge fluid by revolving a helical groove.
Finally, known fluid compressors comprising a helical groove include ones disclosed in Japanese Patent Applications Laid-Open Nos. 5-280478, 7-224776, 4-314987, 2-201097, 5-39789 and 7-35068. These compressors are also provided with a helical groove that revolves to generate pressure. Of these, some comprise a revolving member having a helical groove and contained in an outer case eccentrically while others comprise a helical groove arranged with a reducing pitch. Japanese Patent Application Laid-Open No. 5-1689 discloses a horizontal compressor type oil feeder comprising a helical flow path.
In any known devices comprising a helical seal arranged at the contacting surface portion between a barrel member and a cylindrical core member and designed to raise the pressure being applied to fluid flowing along the helical seal by revolving the helical seal, the cylindrical core member is concentrically arranged in the barrel member. With such an arrangement, only the axial pushing force generated by the revolving helical seal is used to increase the pressure being applied to the fluid contained in the barrel member and hence such an device is poorly adapted to raise the pressure being applied to the fluid.